1. Field of the Invention
The present invention relates to a reciprocating-type compressor for use as a car air conditioner, and more particularly relates to improvements for slidability in a cylinder block forming a cylinder bore.
2. Description of the Prior Art
Reciprocating type compressors are widely used for such as a car air conditioner. Among reciprocating-type compressors, for example, as illustrated in FIG. 1, a swash-plate-type compressor (referred to as a compressor hereinafter) disclosed in Japanese Unexamined Patent Publication (Kokai) No. 62-51776 is constructed as follows. A plurality of cylinder bores 8 are formed in both cylinder blocks 10, 12 in parallel with the shaft center, and a swash plate 16 is mounted on a drive shaft 14 supported by the cylinder blocks 10, 12. A piston 15 is mounted on the swash plate 16 through shoes 13, and the piston 15 is held in a cylinder bore 8 so that the piston 15 can be reciprocated in accordance with the inclination of the swash plate 16. Outside of both cylinder blocks 10, 12, front and rear housings 22, 24 are connected respectively through valve plates by through-bolts 26 which penetrate both cylinder blocks 10, 12. In the front and rear housings 22, 24, there are provided intake chambers 1, 2 communicating with the cylinder bores 8 through intake ports in the valve plate, and also there are provided outlet chambers 3, 4 communicating with the cylinder bores 8 through outlet ports in the valve plate.
In this compressor, when the drive shaft 14 is rotated, the swash plate 16 is rotated and simultaneously fluctuates in accordance with the inclination of the swash plate 16. Due to the fluctuating motion, the pistons 15 are reciprocated in the cylinder bores 8. Due to the foregoing, refrigerant gas in the suction chambers 1, 2 is drawn into the cylinder bores 8, and compressed there. After that, refrigerant gas is discharged into the outlet chambers 3, 4.
However, the cylinder blocks 10, 12 are generally made of an aluminum alloy such as ADC12 (JIS H5302, 1990). It has been made clear that the slidability between the piston 15 and cylinder bore 8 is not satisfactory under severe running conditions.